The present invention relates to a method for setting precious and semiprecious stones, typically diamonds, and to stones and precious stone settings which have been configured for practicing the setting method of the present invention.
French patent specification No. 802,367 discloses forming notches in precious stones, such as in diamonds, for receiving in the notches metallic projections which are formed in walls of the setting, thus securing the stones in place. Variations on the basic stone mounting method of the aforementioned French patent specification are described in U.S. Pat. Nos. 4,738,240 and 4,813,246.
The method described in the 802,367 French specification is particularly useful for obtaining so-called invisible mountings of stones, i.e. mountings in which the stones closely abut one another in the manner which conceals the underlying structure which holds the stones.
Specifically, in the U.S. Pat. No. 4,738,240, a generally horizontally oriented notch is formed at each corner of a square diamond, in the region of the pavilion below the girdle. Each notch comprises two facing surfaces, including a lower surface which extends substantially parallel to the plane of the table of the diamond and an upper surface which makes an angle of about thirty degrees with respect to the lower surface. As in the French specification, the mounting, i.e. setting, contains projections which are designed to engage the notches and thus secure the diamonds.
The U.S. Pat. No. 4,813,246 also describes forming notches at the corners of diamonds, the notches being so miniaturized as to be practically invisible. To set the diamonds, a molding cylinder is used in which the diamonds are placed. Liquefied metal poured into the mold flows into the notches, whereby, upon solidification, pads are formed which constitute the elements of a metal grid which holds the diamonds.
To "invisibly" mount a large number of diamonds, the approach of the prior art has been to notch the diamonds and to mount them in a setting having two or more parallel walls, with metallic projections, e.g. prongs or the like, protruding from these walls for intergaging the notches. Typically, these walls define channels in which the diamonds are set abutting one another in accordance with the invisible mounting method.
Several problems and disadvantages are associated with the approach of the prior art. First, because of manufacturing variations in forming the notches and prongs to obtain a large matrix of diamonds, the fit between at least some of the diamonds and the walls may be imperfect, resulting in too much play of many diamonds and a propensity of these loosely fitted diamonds to fall out.
Secondly, particularly in the case of a ring, a problem arises in that, in accordance with the teachings of the prior art, the walls which form the channels of the setting extend laterally, i.e. transversely to the major plane of the ring. Consequently, when the need arises to downsize the ring to fit a thinner finger, decreasing the diameter of the ring has the effect of causing the lateral walls of the channels to move further apart. This loosens the inter-engagement between the metallic projections on the walls and the notches on the diamonds. Therefore, previously well secured diamonds may fall out or become prone to be easily dislodged from the setting.
Also, metallic projections which are formed on the channel walls in the prior art settings can wear off or break. And the need to form metallic projections involves complexity and added cost which, desirably, should be avoided.